Vehicle suspension system for a steerable wheel

ABSTRACT

The suspension system for a vehicle includes a wheel carrier for supporting a wheel. There is a camber regulating device and a caster regulating device. These regulating devices are disposed on a car body side end of a control arm. There is also a co-regulating device, which is connected to the wheel carrier. Sensors sense the driving state of the vehicle and an electronic control unit receives a signal from the sensor for controlling the camber, caster and toe regulating devices.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicle suspension system for asteerable wheel and, more particularly, to a vehicle suspension systemfor a steerable wheel which correctly changes the camber, the caster andtoe according to the driving condition to which the vehicle is subjectedto.

2. Description of Conventional Art

In general, a vehicle suspension system for a steerable wheel connects ashaft and a frame to each other, and absorbs vibrations and impacts froma road surface while the vehicle is running, thereby improving ridecomfort and stability of the vehicle.

To absorb impacts from a road surface, a vehicle suspension system for asteerable wheel should be connected flexibly in a vertical direction,and to endure driving force, braking force and centrifugal force duringthe vehicle's turning operation applied to a wheel, a vehicle suspensionsystem for a vehicle should be connected firmly in a horizontaldirection.

A vehicle suspension system can be classified as an axle integralsuspension system and an independent suspension system. While an axleintegral suspension system is applied to a large vehicle, for example,buses, trucks and rear axles of passenger cars, an independentsuspension system is applied mainly to an axle of a passenger car. Toimprove ride comfort and stability, an independent suspension system isbisected to act independently.

The present invention relates to an independent suspension system. As avehicle suspension system for a steerable wheel, an independentsuspension system of Macpherson type and that of Wishbone type areapplied widely. The axle is thereby prevented from directly transmittingan impact or vibration from a road surface to the vehicle body, so thatoptimal handling stability and running stability can be obtained.

A vehicle suspension system for a steerable wheel is designed tomaintain a proper position of a vehicle in a vehicle operation as wellas absorb vibrations or impacts transmitted from a road surface to thevehicle body thereby ensuring running stability and handling stability.

In FIG. 9 of the drawings, a vehicle suspension system for a steerablewheel of prior art comprises a wheel carrier 100 rotatably supporting awheel, an upper control arm 102 and a lower control arm 104 connectingthe upper and lower portion of the wheel carrier 100 with a car body anda spring assembling body 108 having a shock absorber 106.

But, in this suspension system, elements (camber, caster and toe) of thewheel alignment are fixed as to predetermined values.

Accordingly, the wheel alignment is fixed in an optimal value for onlyone driving state, this suspension system cannot correspond to anotherdriving state that the wheel receives different load and impact, so thatit has a blind point with respect to ride comfort, stability and so on.

SUMMARY OF THE INVENTION

The objects of the present invention provides a vehicle suspensionsystem for a steerable wheel which properly changes camber, caster andtoe according to the driving condition of the vehicle, thereby improvingride quality and steerability to solve the above problems.

The objects of the present invention are fulfilled by providing avehicle suspension system for a steerable wheel comprising:

a wheel carrier rotatably supporting a wheel;

a camber regulating means which is disposed on car body side ends of thecontrol arm and pushes or pulls the control arm to a wheel side therebyregulating a camber angle;

a caster regulating means which is disposed on the car body side ends ofthe control arm and moves the control arm to the front and the rear of avehicle thereby regulating a caster angle;

a toe regulating means which is connected with the wheel carrier therebyregulating a toe;

sensors sensing a driving state of the vehicle; and

an electronic control unit 3 receiving signals from the sensors andcontrolling the camber regulating means, the caster regulating means andthe toe regulating means.

Further, the present invention provides the vehicle suspension systemfor the steerable wheel, wherein the camber regulating means includes:

a fixed rod rotatably connected with the car body side ends of thecontrol arm;

a hinged plate which is rotatably connected with both side ends of thefixed rods and is hinged on the car body;

an actuator which is rotatably connected with the fixed rod and movesthe fixed rod in the direction of car width; and

a direction converting valve controlling the flowing direction ofpressurized fluid supplied to the actuator.

Further, the present invention provides the vehicle suspension systemfor the steerable wheel, wherein the caster regulating means includes:

a fixed rod rotatably connected with the car body side ends of thecontrol arm;

mail screw portions provided on both ends of the fixed rod;

a worm gear fixed on one side end of the fixed rod;

a worm for rotating the worm gear;

a ball-screw which is fixed to the hinged plate, in which the male screwportion is inserted thereby making the fixed rod to rotate and move infront and rear direction of the vehicle; and

a driving means for rotating the worm.

Further, the present invention provides the vehicle suspension systemfor the steerable wheel, wherein the toe regulating means includes:

a connecting link connected with the wheel carrier;

a pivot member which is hinged on the car body and is connected with theconnecting link;

an actuator rotating the pivot member; and

a direction converting valve controlling the flowing direction ofpressurized fluid supplied to the actuator.

Further, the present invention provides the vehicle suspension systemfor the steerable wheel, wherein the fixed rod includes a first fixedrod rotatably connected with car body side ends of the control arm and asecond fixed rod rotatably connected with the actuator.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention and wherein:

FIG. 1 is a perspective view of an embodiment of a suspension systemaccording to the invention;

FIG. 2 is a schematic view of a camber regulating means applied to anembodiment of a suspension system according to the present invention;

FIG. 3 is a schematic view of a caster regulating means applied to anembodiment of a suspension system according to the present invention;

FIGS. 4A and FIG. 4B are side views showing an angular displacement ofcaster;

FIG. 5 is a schematic view of a toe regulating means applied to anembodiment of a suspension system according to the present invention;

FIG. 6 is a hydraulic circuit diagram applied to an embodiment of asuspension system according to the present invention;

FIG. 7 shows an operation of a camber regulating means applied to anembodiment of a suspension system according to the present invention;

FIG. 8 shows an operation of a toe regulating means applied to anembodiment of a suspension system according to the present invention;and

FIG. 9 is a schematic view of a suspension system of a prior artsuspension system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following is the description of the preferred embodiments accordingto the present invention. In the drawings, like numerals have been usedto identify like elements in each figure.

In FIG. 1, a suspension system according to the present invention thatincludes a wheel carrier 2 rotatably supporting a wheel (not shown),upper and lower control arms 3 and 4 connecting upper and lower portionsof the wheel carrier 2 with a car body, camber and caster regulatingmeans 5 and 6 which are disposed on ends of the car body side of theupper and lower control arms 3 and 4 thereby regulating a camber and acaster respectively and a toe regulating means 7 connected to the wheelcarrier 2 thereby regulating a toe.

A hollow hole 20 is formed on a central portion of the wheel carrier 2and a driving shaft (not shown) passes therethrough and the wheel isdisposed on ends of the driving shaft. Further, the upper and lowercontrol arms 3 and 4, of which connecting portions 30 and 40 of wheelside ends are connected with the wheel carrier 2 by a ball joint, and ofwhich connecting portions 31 and 32, and 41 and 42 of car body side endsare connected with the car body, so that it is possible that the wheelsrise and fall according to a state of a road surface and a drivingcondition.

The camber regulating means 5 includes the upper and lower control arms3 and 4 rotatably connected with the wheel carrier 2 respectively in thevertical direction of the car body, hinged plates 332, 333, 432 and 433hinged on the car body, first fixed rods 330 and 430 which are rotatablyinserted into the connecting portions 31 and 32, and 41 and 42 of thecar body side ends of the control arms 3 and 4 respectively and arerotatably connected with the hinged plates 332 and 333, and 432 and 433respectively, second fixed rods 331 and 431 rotatably connected with thehinged plates 332 and 333, and 432 and 433 and actuators 34 and 44having piston rods 340 and 440 rotatably connected with the second fixedrods 331 and 431 respectively.

With reference to FIG. 1 and FIG. 3 together, the caster regulatingmeans 6 includes the lower control arm 4, the first fixed rod 430connected with the lower control arm 4 to be rotated but not to belinearly moved with respect to the lower control arm 4, male screwportions 600 and 610 formed on both side ends of the first fixed rods430, lower hinged plates 432 and 433, ball screws 60 and 61 which aremounted on the hinged plates 432 and 433 and are combined with the malescrew portions 600 and 610 thereby making the first fixed rod 430 torotate and move, a worm gear 621 fixed on the male screw portion 610, adirect current motor 62 disposed on one surface of the hinged plate 433and a worm 620 which is disposed on an end of the shaft of the directcurrent motor and rotates the worm gear.

With reference to FIG. 5, the toe regulating means 7 includes aconnecting link 70 of which one side end is connected with the wheelcarrier 2 by a ball joint, a pivot member 71 having a horizontal portion710 and a vertical portion 711 and an actuator 72, wherein theconnecting link 70 is rotatably connected with the vertical potion 711in the vertical direction of the car body and the piston rod 720 of theactuator 72 is rotatably connected with the horizontal portion 710.

The following is the description of the camber regulating means 5.

With reference to FIG. 2, an electronic control unit 9 receives signalsfrom sensors sensing the vehicle's driving state, like a vehicle speedsensor 90, a steering angle sensor 91, a side force sensor 92 and so on.The electronic control unit 9 compares these signals with predetermineddata and decides them thereby controlling direction converting valves 35and 45 for regulating the flowing direction of pressurized fluid from ahydraulic pump 8. Then, the pressurized fluid passed through thedirection converting valve 35 and 45 is supplied with car body sidehydraulic chambers 341 and 441 or wheel side hydraulic chambers 342 and442 of the actuators 34 and 44 thereby pushing or pulling piston rods340 and 440. The hinged plates 333 and 433, which are rotatablyconnected with the piston rods 340 and 440 and are hinged with the carbody by one side, rotate respectively and push or pull the upper andlower control arms 3 and 4 rotatably connected with the wheel carrier 2thereby regulating the camber and tread.

FIG. 7 shows an operation of the camber regulating means 5 of theembodiment, wherein the camber regulating means 5 regulates the wheel 1,indicated by imaginary lines, which are broken lines.

With reference to FIG. 3, the following is the description of the casterregulating means 6.

The electronic control unit rotates the direct current motor 62clockwise or counterclockwise according to the driving state of thevehicle. Then the first fixed rod 430 rotates and moves upward anddownward when viewed from the drawing so that the upper control arm 4connected with the first fixed rod 430 also moves upward and downward.Accordingly, a caster angle is regulated thereby. When the vehicle speedis middle or high, as shown by a dotted line in the drawing, the lowercontrol arm 4 moves downward so that the caster angle increases therebyimproving the straight drive stability of the vehicle. On the contrary,when the vehicle speed is low, the lower control arm 4 moves upward sothat the caster angle reduces thereby improving the steerability.

FIG. 4A is a side view showing an angular displacement of caster in casethat the caster regulating means 6 is connected with the lower controlarm 4, and FIG. 4B is a side view showing an angular displacement ofcaster in case that the caster regulating means 6 is connected with theupper control arm 3 (not disclosed), wherein a reference numeral "1"indicates a wheel.

With reference to FIG. 5, the following is the description of the toeregulating means 7.

The electronic control unit makes the pressurized fluid to be suppliedwith the actuator 72 according to the driving state of the vehiclethereby pushing or pulling the piston rod 720. Then, the pivot member 71pushes or pulls the connecting link 70 thereby regulating the toe. FIG.8 shows an operation of the toe regulating means 7.

FIG. 6 is a hydraulic circuit diagram applied to an embodiment of asuspension system according to the present invention, which is describedbelow.

When the electronic control unit 9 receives the signals from each of thesensors 90, 91 and 92, it compares the signals with the predetermineddata and decides output signals thereby controlling each of thedirection converting valves 35, 45 and 74, so that the actuators 34, 44and 72 as well as the direct current motor 62 are properly operated.

According to the present invention, each regulating means 5, 6 and 7controlled by the electronic control unit maintains an optimal state ofthe wheel alignment according to the diving state of the vehicle therebyimproving ride quality and stability of the vehicle.

FIG. 9 illustrated prior art which has been described above in detail.

Although preferred embodiments of the present invention have beendescribed in detail hereinabove, it should be clearly understood thatmany variations and/or modifications of the basic inventive conceptsherein taught which may appear to those skilled in the present art willstill fall within the spirit and scope of the present invention, asdefined in the appended claims.

What is claimed is:
 1. A vehicle suspension system for a steerable wheelcomprising:a wheel carrier rotatably supporting a wheel; camberregulating means which is disposed on car body side ends of a controlarm for pushing or pulling said control arm to a wheel side therebyregulating a camber angle; caster regulating means which is disposed onthe car body side ends of said control arm for moving said control armto a front and a rear of the vehicle thereby regulating a caster angle;toe regulating means which is connected with said wheel carrier therebyregulating a toe; sensors sensing a driving state of the vehicle; and anelectronic control unit for receiving signals from said sensors andcontrolling said camber regulating means, said caster regulating meansand said toe regulating means.
 2. The vehicle suspension system for thesteerable wheel according to claim 1, wherein said camber regulatingmeans includes:a fixed rod rotatably connected with the car body sideends of said control arm; a hinged plate which is rotatably connectedwith both side ends of the fixed rod and is hinged on the car body; anactuator which is rotatably connected with the fixed rod and moves thefixed rod in the direction of car width; and a direction convertingvalve controlling the flowing direction of pressurized fluid supplied tothe actuator.
 3. The vehicle suspension system for the steerable wheelaccording to claim 1, wherein said caster regulating means includes:afixed rod rotatably connected with the car body side ends of saidcontrol arm; mail screw portions provided on both ends of the fixed rod;a worm gear fixed on one side end of the fixed rod; a worm for rotatingthe worm gear; a ball-screw which is fixed to the hinged plate, in whichthe male screw portion is inserted thereby making the fixed rod torotate and move in the front and the rear direction of the vehicle; anddriving means for rotating the worm.
 4. The vehicle suspension systemfor the steerable wheel according to claim 1, wherein said toeregulating means includes:a connecting link connected with said wheelcarrier; a pivot member which is hinged on the car body and is connectedwith the connecting link; an actuator rotating the pivot member; and adirection converting valve controlling the flowing direction ofpressurized fluid supplied to the actuator.
 5. The vehicle suspensionsystem for the steerable wheel according to claim 2, wherein the fixedrod includes a first fixed rod rotatably connected with the car bodyside ends of said control arm and a second fixed rod rotatably connectedwith the actuator.